A furnace roller assembly, or furnace roll or roller, is used to move a metal product through a furnace. Typically the metal product is a flat sheet, or slab, that travels along the length of the furnace by making surface contact with structural elements attached to each furnace roller assembly installed along the length of the furnace. U.S. Pat. No. 5,833,455 relates various types of furnaces, including roller hearth tunnel furnaces, and the metal products moving through the furnaces in the description of the prior art. The furnace roller assembly rotates by connection to a suitable drive that may include a motor, and is typically cooled by internal water flow.
The radially outward surface of the rim of a metallic tire is typically used in a furnace roller as the structural element making friction contact with metal product, as shown for example, in U.S. Pat. Nos. 5,230,618 and 5,341,568 where multiple tires are spaced apart from each other along the arbor, or shaft, of the furnace roller. In these arrangements the shaft is oriented perpendicular to the direction of the metal product moving through the furnace, and the radially outward surfaces of the rims are parallel to the direction of the moving metal product.
As mentioned in the description of related art in U.S. Pat. No. 6,435,867 B1, the structural interface between a tire and the arbor (or shaft) of the furnace roller is critical to designing a furnace tire that will withstand the harsh furnace operating environment. Furnace tire life is a function of temperature of the metal product passing over the rim of the tire; metal product heating may be limited based upon the requirement to maintain a minimum service life for each installed tire. Further tire tracking, or skid marks, can result on the metal product from the fixed position of each tire's rim relative to the length of the metal product as it passes through the furnace. Depending upon the use of the product leaving the furnace, further processing of the product may be required to remove the tire tracking.
One objective of the present invention is to provide a method of moving metal product through a tunnel roller furnace with fewer limitations on the maximum temperature of the product based upon furnace roller life.
Another objective of the present invention is to provide a furnace roller that will not leave tire tracks, or other blemishes, on the product as it passes through the furnace.